Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple user equipment devices. Each user equipment (UE) communicates with one or more base stations, such as an evolved Node B (eNB) via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the eNBs to the UEs, and the reverse link (or uplink) refers to the communication link from the UEs to the eNBs. This communication link may be established via a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system. In this regard, the UEs can access wireless network via one or more eNBs.
Additionally, LTE, or other scheduled wireless communication technologies, can be extended for use in unlicensed frequency bands where resources may be available only for opportunistic transmissions. For example, LTE can be utilized for communicating over a frequency band of Institute of Electrical and Electronics Engineers (IEEE) 802.11 (WiFi), and LTE eNBs may thus make opportunistic transmissions by using listen-before-talk (LBT) frames when the frequency band becomes available for transmission. UEs communicating with the eNBs monitor each downlink subframe in the LBT frame (and/or subsequent LBT frames) to detect and/or decode communications intended for the UEs. This may be inefficient for the UE, as the UE continues to monitor without knowing if downlink communications are scheduled for the UE in the LBT frame.
In LTE, for example, UEs can be configured to operate in a discontinuous receive (DRX) mode where the UE has activated receiving resources for an ON duration and deactivated receiving resources for an OFF duration to conserve power otherwise utilized by monitoring wireless communication channels. In unlicensed frequency bands, however, DRX cycle timing may not align with the eNB acquiring a channel of the frequency band for transmission (e.g., the eNB successfully performing clear channel assessment (CCA) of the frequency band). Thus, using DRX, as currently configured for LTE, for communicating in unlicensed frequency bands may result in the UE not receiving communications from the eNB (e.g., where the eNB acquires and transmits communications over the channel while the UE is in the DRX OFF duration).